Absorption refrigeration



Dec. 18, 1951 w. G. KGEL ABsoRPTIoN REFRIGERATION 2 SHEETS-SHEET l Original Filed Dec. 15, 1944 W- INVENTOR.

Dec. 18, 1951 w. G. KGEL Y Re 23,442

BSORPTION REFRIGERATION Original Filed DBC. l5, 1944 y 2 SHEETS--SHEET 2 IN V EN TOR.

Ressued Dec. 18, 1951 UNITED STATE S PATENT OFFICE ABSORPTION REFRIGERATIN Original No.

Serial No. 568,269, December 15,

2,538,010, dated January 16, 1951,

1944. Application for reissue ctober 20, 1951, Serial No. 252,229; In Sweden March 3, 1944 13 Claims.

(Cl. (i2-119.5)

Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions. made by reissue.

This invention relates to refrigeration and more particularly to absorption refrigeration apparatus of the pressure equalizing type employing an inert gas or auxiliary pressure equalizing agent.

It is an object of the invention to provide an improvement to obtain better liquid circulation in heat operated absorption refrigeration apparatus of this type having a vapor-liquid lift-l tube or pump which receives absorption solution from an absorber through a passagepf a liquid heat exchanger, the inlet of the lift tube or pump being at a lower level than the outlet of the liquid heat exchanger passage from which solution flows to the lift tube or pump.

The above and other objects and advantages of the invention will be better understood from the following description taken in `connection with the accompanying drawing forming a part of the specification, and of which:

Fig. l is a fragmentary View of absorption refrigeration apparatus embodyingv the invention; and

Figs. 2 and 3 are fragmentary views of refrigeration apparatus Which are similar to Fig. 1 i1- lustrating further embodiments of the invention.

In Fig. l, reference numeral IU designates a tube which serves as a heating tube or flue and in the lower heat input end of which a heat source, such as a burner 6, for example, is positioned. The liquid heat exchanger II of the apparatus, which is in the form of a helical coil, is disposed concentrically about the ue I0. At its lower end the inner tube I2 of the exchanger communicates with a conduit I3 which is ccnnected at its upper end to an absorber vessel I4 which is adapted to hold a body of absorbent rich in refrigerant. At its upper end the tube I2 is connected to a vertically disposed conduit I5 which is closed at its lower end. The conduit I5 is heat conductively connected, as by Welding, for example, with the flue I0 along a common generatrix. The upper end of conduit I5 com- -municates with a vapor conduit I6 leading to the condenser of the apparatus, not shown.

The conduit I5 serves `as the boiler proper of the apparatus in which the main or principal part of the refrigerant vapor is expelled. The rich solution ows from the absorber vessel I4 through the inner tube or passage I2 of the liquid heat exchanger II into the conduit or pipe I5 in which it is heated to the boiling point or temperature to expel vapor therefrom, such solution owing downward toward the bottom of the pipe or boiler I5 with decreasing concentration of refrigerant. A vapor-liquid lift tube or pump I9 for effecting circulation of liquid is connected at its lower end to the lower end of the boiler I5 and at its upper end to a standpipe I'I which is vertically disposed and connected at its upper end to the lvapor conduit I6. Raised solution is introduced into the upper end of the standpipe II whose lower end communicates with the outer tube or passage of the liquid heat exchanger Il through which solution flows into a conduit I8 which, in turn, is connected at its upper end to the air-cooled absorber of the apparatus which may be in the form of a tubular coil l.

In a well known manner, inert gas rich in refrigerant enters absorber vessel I4 through a conduit 8 and inert gas Weak in refrigerant passes from the upper end of absorber I througha conduit 9. lThe lift tube or pump I9 is welded to the flue III along a common generatrix from a point 20 up to a point 2 I. By way of example and Without limitation the distance between the points 20 and 2| desirably should not be less than 50 mm.

and preferably should exceed mm.

It has already been mentioned that the boiling of refrigerant takes place chiefly in the pipev I5 which serves as the boiler proper. The solution flowing to the bottom of the pipe I5 will therefore be relatively poor in refrigerant and the lift tube or pump I9 accordingly Will function and operate at a higher temperature which is dependent upon the lower refrigerant concentration of the solution. When the rate at which refrigerant is expelled from solution in pipe I5 is not too excessive, the lift tube or pump I9 in certain cases may be formed as a coil disposed about the lower end of the flue I0 from which a riser pipe extends upward which is thermally separated from the ilue. However, it generally is extremely important to provide the lift tube or pump I9 in the manner illustrated in Fig. 1 which is the preferred manner of practicing the invention. By extending the heat conductive connection between the flue I0 and the pump tube I9 upwardly in a vertical direction to a point which is at a-level with or higher than the liquid level in the absorber vessel I4, satisfactory operation of the liquid pump is insured,

particularly when the refrigeration apparatus is.

started following a shut-down period. In such case the size of the reaction head formed by the liquid column in pipe I5 is relatively important.

The raised solution, the refrigerant concentration of which is further decreased by expulsion of refrigerant in the pump I9, is introduced into the standpipe I1 in which further expulsion of refrigerant from solution may take place if desired. In such case the standpipe Il may be arranged in heat conductive relation with the flue I0. Usually expulsion of refrigerant from solution in the standpipe I'I is unnecessary and not desirable because such expelled vapor will contain a relatively large amount of absorbent vapor. However, in certain cases in which particular utilization of the heat contents of the heating gases passing through the upper parts of the flue is desired, a heat conductive connection may be provided between the standpipe I'I and the flue I so that the poor solution will ilow downwardly through the standpipe at an unchanged or somewhat increased temperature. In this manner, the heat contents of the flue gases will be utilized by such heat exchange. Owing to the low boiler level there may otherwise ensue difficulties in the rational utilization of the heat contents of the flue gases.

Another embodiment of the invention is diagrammatically shown in Fig. 2 which illustrates a part of the absorption liquid circuit, it being understood that such circuit also includes an absorber 'I and connections 8 and 9 similar to those shown in Fig. l and that corresponding parts are referred to by the same reference numerals. In Fig. 2 the suction side of the pump I9 is connected to a tube 26 which in turn is connect'ed to the boiler I5. and also to an auxiliary boiler 25 which comprises a tube heat conductively connected with the ue Ill and having a closed lower end. The upper end of auxiliary boiler 25 communicates with the boiler I5 at a point somewhat below the liquid level in the latter. In certain cases it may be advantageous to omit or limit the heat conductive connection between the auxiliary boiler 25 and the flue I0. With this arrangement the rich solution in the surface layer of the boiler I5 is sucked or drawn through the auxiliary boiler 25 into the pump tube I9 together with poor solution from the main boiler I5.

The pump will therefore operate with a solution having higher concentration of refrigerant than in the embodiment of Fig.. 1 and consequently the refrigerant concentration of the vapor lpassing from the pump I9 will be correspondingly higher. In certain cases it may even be advantageous to connect the pump or lift tube I9 only to the auxiliary boiler 2|. In such case, however, special measures should be taken for effecting circulation of the liquid held in the main boiler I5, as 'by dividing the boiler pipe I5 by a partition into two sections which are in communcation with each other at a region below the lower end of the partition and into one of which the conduit I2 is connected.

Where it is desired to feed the pump I9 with solution that is rich in refrigerant, it is possible to practice the invention in a manner which differs from the embodiment of Fig. 1 by limiting or interrupting the heat-conducting contact between thek boiler pipek I5 and the flue I9, so that expulsion of refrigerant from solution will take place chieily in the lift tube or pump I9. Sho-uld the development of gas in said pump be of an order unsuitable for normal circulation of liquid, the standpipe. I'I may `be heat conductively connected with the flue, thus functioning as the boiler proper of the apparatus. In this case the amount of heat transferred from the heat source or heating tube II) will be distributed between the pump I9 and the tube I1. Such an arrangement of aV vapor expulsion unit or boiler system is illustrated in Fig. 3 in which parts like those shown in Figs. l and 2 are referred to by the same reference numbers, it being understood that the absorption solution circuit of Fig. 3 also includes an absorber 'I and connections B and 9 like those shown in Fig. 1. As in the previously described embodiments cf Figs. 1 and 2, the extreme lower end of the stanclpipe or conduit 17 is connected to the outer passage of the vertically extending liquid heat exchanger coil 11 at the upper end of such coil.

The invention is chiefly intended to be applied to domestic refrigerating apparatus which operates continuously and employs an inert gas, such as hydrogen, for example. Further, ammonia may be employed as the refrigerant and water as the absorbent. However, the invention is not toV be limited to the specificembodiments which are illustrated and described above. The arrangement of the vapor expulsion unit or boiler system, inclusive of the heat exchanger, may be modified in many respects Within the scope of vthe invention. However, the greatest advantage is offered by the type of'boiler illustrated herein because it is possible to establish in a very simple manner suitable conditions for effecting satisfactory heat distribution among the diierent liquid spaces of the vapor expulsion unit or boiler system, the

number of which is at least two and in certain cases may be increased to four or division into vertical sections. A y

For completely utilizing the advantages of the invention the construction of the boiler is of great importance. To prevent corrosion and for even ve by economical reasons, it is desirable to reduce the` number of welded seams to a minimum. From a thermal point of view it is advantageous to use tubes which are as narrow as possible.v By way of an example and without limitation it may be stated that in the embodiment of Fig. 3 the boiler pipe I5 may be given the same dimension as the pump tube. The pipe I5 and the pump I9 may `be formed from the legs of a seamless U-tube in which case the standpipe I'I' must obviously be connected heat conductively with the ue, thus functioning as the boiler of the apparatus. If it isv not possible to choose the same dimension for the pipe I5 and the pump I9, it is in most cases possible to select a dimension for the pipe I5 which will be between the dimensions of the tubes II and I9. In a similar manner the tube I`I of Fig. 1 may be selected so that its cross-sectional area wi-ll be between and I5.

In view of the foregoing it will now be understood that the lift tube or pump I9 extends downwardly from the upper end of liquid heat exchanger I-I. The pump I9 does not form a direct upward extension or continuation ofY the inner pipe I2 of the liquid heat exchanger but instead is connected to the lower end of the pipe or conduit I5. Such an arrangement of the parts of the vapor expulsion unit or boiler system is of that of tubes I9 distinct advantage by reason of the low posi-tion at which the heat source is placed in the lower heat input end of the heating tube or ue Ill. If the pump or lift tube I9 extended upwardly from the region the innerV pipe i2 of the liquid heat exchanger is connected to the boiler pipe- I5", the liquid reaction head under which solution would be raised would be' relativelysmall. Also, the heat supply to the pump pipe I!)l in such an arrangement would not be eiected under the most satisfactory conditions. v

In..the several embodiments. 4of thev invention which have been shown and described, the heating tube I and vertical conduits I5 and I1 disposed alongside the heating tube constitute a vapor expulsion unit in which one of the vertical conduits is heat conductively connected to the heating tube and in thermal relation therewith. Solution flows in an unbroken stream from the outlet of the absorber vessel I4 to the lower end of the pump I9 in a path of flow which includes conduit I3, inner pipe I2 of the liquid heat exchanger and conduit I5. Thus, the liquid column in conduit I freely communicates with the outlet of the absorber by an unbroken liquid body, and liquid flows entirely by gravity from the outlet of vessel I4 to a region of conduit I5 removed from the lower end thereof. The liquid surface level in the conduit I5 is above the highest point of the liquid heat exchanger and approximately at the same level as the liquid body in the absorber vessel I4. Also, the liquid surface level in the conduit I5 is above the region solution is conducted thereto through the inner pipe I2 of the liquid heat exchanger.

It will be seen that both of the heat exchanger pipes of helical form provide ascending paths of flow for any vapor in the heat exchanger passages which is always vented into the conduits I5 and I1, respectively. Solution passing from the outlet end of absorber vessel I4 is conducted through the inner pipe I2 of heat exchanger II only in an ascending path of flow. Further, the lift tube or pump pipe I9 is thermally connected to the heating tube I0 in a zone extending between the liquid surface level in conduit I5 and the lowest part of the heat exchanger II so that vapor will be expelled from solution in the lift pipe and liquid will be raised therein by vapor lift action under the influence of the reaction head formed by the liquid column in the conduit I5.

In all of the embodiments shown the lift tube I9 and conduits I5 and I1 in their entirety are disposed outside the heating tube or flue I0. In the embodiments of Figs. 1 and 2 the conduit I'I is thermally separated or spaced from the heating tube III while in Fig. 3 the conduit I5 is thermally separated or spaced from the heating tube or flue. In all of the embodiments shown and described the lower heat input end of the heating tube or flue I0 extends downwardly below the lowest point of theliquid heat exchanger I I, and

the highest point of the liquid heat exchanger is located at a region intermediate the upper and lower ends of the iiue. In all of the embodiments the liquid heat exchanger I I, which is in the form of a helical coil, is disposed about the heating tube or flue [l1] 10 and the conduit I5.

While particular embodiments of the invention have been shown and described, such variations and modications are contemplated as fall within the true spirit and scope of the invention, as pointed out in the following claims. [Howeven the provision of the liquid pocket in conduit I1 below the connection of the outer passage of the liquid heat exchanger II thereto, which is shown in Fig. 3, is being claimed in copending application Serial No. 673,669, filed May 31, 1946.]

I claim:

l. In an absorption refrigeration system of the inert gas type including an absorber, a liquid heat exchanger having a plurality of passages, a vapor expulsion unit comprising an upright heating tube, first and second upright conduits alongside of said heating tube and at least one of which is in heat conductive relation therewith, the aforesaid parts being so connected that solution flows in an unbroken stream from the outlet of said absorber through a passage of said heat exchanger and first conduit into the lower end of said lift pipe and [form] forms a liquid column in said first conduit having a liquid surface level which is above the highest point of said heat exchanger, and solution entering from said lift pipe forms a liquid column in said second conduit from which solution flows through another passage of said heat exchanger to the inlet of said absorber, said heat exchanger being so arranged and connected in the system that vapor in any part of the passages thereof is always vented into said conduits, and said lift pipe having a part thermally connected to said heating tube in a zone extending between the liquid surface level in said iirst conduit and the lowest part of said heat exchanger to cause expulsion of vapor from solution in said pipe and raise liquid therein by vapor lift action under the influence of a reaction head formed by the liquid column in said first conduit.

2. In an absorption refrigeration system of the inert gas type, a [circnit] circuit for absorption solution including an absorber, a liquid heat exchanger and a compact vapor expulsion unit comprising a vertically extending flue, iirst and second conduits substantially parallel to said flue and a lift pipe communicating with the lower part of said first conduit and upper part of said second conduit for raising liquid therein by vapor lift action, both of said conduits and said lift [pipes] pipe in their entirety being disposed outside said flue, said first conduit being in thermal relation with the exterior surface of said heating flue and said second conduit being thermally separated therefrom, the aforementioned parts being so constructed and connected in said circuit that solution flows in an unbroken stream from the outlet of said absorber through said heat exchanger and first conduit into the lower end of said lift lpipe and forms a liquid column in said first conduit having a liquid surface level above the highest point of said heat exchanger, and solution entering from said lift pipe forms a liquid column in said second conduit and from which solution flows through said heat exchanger to the inlet of said absorber, and said lift pipe having a zone adjacent the lower end thereof thermally connected to the exterior surface of said heating flue to cause expulsion of vapor from solution in such zone and raise liquid in said pipe by Vapor lift action under the iniiuence of a reaction head formed by the liquid column in said first conduit.

3. In an absorption refrigeration system of the inert gas type including a refrigerant vapor supply line, an upright heating flue having a lower heat input end, a circuit for circulation of absorption solution including an absorber, a vertically extending liquid heat exchanger having its highest point intermediate the ends of said flue, and a vapor expulsion unit comprising first and second upright conduits, a first connection including said heat exchanger for conducting solution from said absorber to said first conduit at a region removed from the lower end thereof, the solution flowing from said absorber through said first connection having only an ascending path of flow in said heat exchanger, a second connection including said heat exchanger for conducting solution from said second conduit to said absorber, a lift pipe which is connected at its lower and upper ends to said first and second conduits, respectively, one of said conduits being in thermal` relation with said heating nue, conduit means `for conducting vapor from the upper ends of said conduits to said vapor supply line, said first connection being so formed that said flrst conduit contains a liquid column whose surface level is above the region solution is conducted thereto, and also above the highest point of said heat exchanger, and said lift pipe having a part in thermal relation with said iiue along a zone extending downwardly below the highest point of said heat exchanger to cause expulsion of vapor from solution in said pipe and raise liquid therein by vapor lift action under the influence of a reaction head formed by the liquid column in said rst conduit.

4. In an absorption refrigerating apparatus of the inert gas type including a refrigerant vapor supply line, an absorber, and a liquid heat exchangena vapor expulsion unit coinprisinng comprising an upright heating tube, a first upright conduit so connected as to contain a liquid column freely communicating through said heat exchanger with the liquid outlet of said absorber, a second upright conduit so connected. as to contain a liquid column communicating freely through said heat exchanger with the liquid inlet of said absorber, one of said conduits being thermally connected to said heating tube, conduit means for conducting vapor from the upper ends of said conduits to said vapor supply line, a vapor lift pipe having the lower end thereof connected to said rst conduit and the upper end thereof to said second conduit, said lift pipe having a part thermally connected to said heating tube in a zone extending downwardly below the highest point of said heat exchanger to cause expulsion of vapor from solution in said pipe and raise liquid therein by vapor lift action under the influence of a reaction head formed by the liquid column in said rst conduit, and a third upright conduit connected to said first conduit below the upper end of the liquid column contained in the latter, the lower end of said lift pipe also being connected to said third conduit.

5. In an absorption relrigerating apparatus of the inert gas type including a refrigerant vapor supply line, an absorber, and a liquid heat exchanger, a vapor expulsion unit comprising an upright heating tube, a iirst upright conduit so connected as to contain a liquid column freely communicating through said heat exchanger with the liquid outlet of said absorber, a second upright conduit so connected as to contain a. liquid column communicating freely through said heat exchanger with the liquid inlet of said absorber, one of said conduits being thermally connected to said heating tube, conduit means for conducting vapor from the upper ends of saidy conduits to said vapor supply line, a vapor lift pipe having the lower end thereof connected to said first conduit and the upper end thereof to said second conduit, and said lift pipe having a part thermally connected to said heating tube in a zone extending downwardly below the highest point of said heat exchanger to cause expulsion of vapor from solution in said pipe and raise liquid therein by vapor lift action under the influence of a reaction head formed by the liquid column in said rst conduit, one of said conduits comprising two parallel branches.

6. In absorption refrigeration apparatus having a refrigerant vapor supply line, a circuit for circulation of absorption solution including an absorber, a vertically extending liquid heat exchanger and a vapor expulsion unit comprising an upright heating tube having a lower heat input end terminating at a level lower than the lowest point of said heat exchanger, first and second upright conduits, said first conduit being so connected in said circuit as to contain a liquid column communicating through said heat exchanger with the outlet of said absorber by an unbroken body of liquid and said second conduit being so connected as to contain a liquid column communicating through said heat exchanger with the inlet ci said absorber, said heat exchanger being in the form of a coil disposed about said heating tube and constructed and arranged to vent vapor therefrom to said first and second conduits, the surface level of the liquid column in said first conduit being above the highest point of said heat exchanger, one of said conduits being in therm l relation with said heating tube, said vapor supply line being connected to receive vapor from the upper ends oi said first and second conduits, and a lift pipe connected to raise liquid from said first conduit to said second conduit which includes a heat receiving and Avapor forming part in thermal relation with said heating tube along a Zone extending downwardly below the highest point of said heat exchanger.

'7. In absorption refrigeration apparatus having a refrigerant vapor Supply line, a circuit for cireu'aticn absorption solution including an absorber, a vertically extending liquid heat eX- changer and a vapor expulsion unit comprising an upright heating tube having a lower heat input end terminating at a level lower than the lowest point of said'heat exchanger, first and second upright conduits, said rst conduit being so connected in said circuit as to contain a liquid column communicating through said heat exchanger with the outlet of said absorber by an unbroken body of liquid and said second conduit being so connected as to contain a liquid column communicating through said heat exchanger with the inlet of saidl absorber, said heat exchanger being in the form oi a coil disposed about said heating tube and said first conduit, the surface level of the liquid column in said first conduit being above the highest point of said heat exchanger, one of said conduits being in thermal relation with said heating tube, said vapo-r supply line being connect-ed to receive vapor from the upper ends cf said iirst andv second conduits, and a lift pipe connected to raise liquid from said rst conduit tc said second conduit which includes a heat receiving and vapor forming part in thermal relation with said heating tube along a zone extending downwardly below the highest point of said heat exchanger. v

8. In absorption refrigeration apparatus having a refrigerant vapor Supply line, a circuit for circulation of absorption solution including an absorber, a vertically extending liquid heat exchanger and a vapor expulsion unit comprising an upright heating tube having a lower heat input end terminating at a level lower than the lowest point of said heat exchanger, first and second uprights conduits, said rst conduit being so connected in said circuit as to contain a liquid column communicating through said heat exchanger with the outlet of said absorber by an unbroken body of liquid and said second conduit being so connected as to contain a liquid column corn,- municating through said heat exchanger with the inlet of said absorber, the surface level of the liquid column in said first conduit being above the highest point of said heat exchanger which tube, one of said conduit being in thermal relation with said heating tube, said vapor supply line being connected to receive vapor from the upper ends of Said first and second conduits, and a lift pipe connected to raise liquid from said first conduit to said second conduit which includes a heat receiving and vapor forming part in thermal relation with said heating tube along a Zone extending downwardly below the highest point of said heat exchanger.

9. In an -absorption refrigeration system of the inert gas type including a refrigerant Vapor supply line, an absorber, a liquid heat exchanger, a vapor expulsion unit comprising an upright heating tube, a first upright conduit thermally separated from said tube, a second upright conduit in thermal relation with said tube, said vapor supply line being connected to receive vapor from the upper ends of said first and second conduits, a lift pipe communicating with the lower part of said first conduit and the upper part of said second conduit, the aforesaid parts being so connected in the system that solution flows in an unbroken stream from the outlet of said absorber through said heat exchanger and first conduit into the lower end of said lift pipe and forms a liquid column in said first conduit having a liquid surface level which is above the highest point of said liquid heat exchanger, and solution entering from said lift pipe forms a liquid column in said second conduit from which solution flows through said heat exchanger to the inlet of said absorber, and said lift pipe having a part thermally connected to said heating tube in a zone extending between the liquid surface level in said first conduit and the lowest point of said heat exchanger to cause expulsion of vapor from solution in said pipe and raise liquid therein by vapor lift action under the influence of a reaction head formed by the liquid column in said first conduit.

10. In an absorption refrigeration system of the inert gas type including a refrigerant vapor supply line, an upright heating flue having a lower heat input end, a circuit for circulation of absorption solution including an absorber, a vertically extending liquid heat exchanger having its highest point intermediate the ends of said iiue, and a vapor expulsion unit comprising a first upright conduit thermally separated from said flue, a first connection including said heat exchanger for conducting solution from said absorber to i said first conduit at a region removed from the lower end thereof, a second upright conduit in thermal relation with said flue having its upper end communicating with said vapor supply line, a second connection including said heat exchanger for conducting solution from said second conduit to said absorber, a lift pipe which is connected at its lower and upper ends to said first and second conduits, respectively, said rst connection being so formed that said first conduit contains a liquid column whose surface level is above the region solution is conducted thereto, and said lift pipe having a part in thermal relation with said flue along a zone extending downwardly below the highest point of said heat exchanger to cause expulsion of vapor from solution in said pipe and raise liquid therein by vapor lift action under the influence of a reaction head formed by the liquid column in said first conduit.

11. In an absorption refrigeration system of the inert gas type including a refrigerant vapor supply line, an upright heating flue having a lower heat input end, a circuit for circulation of absorption solution including an absorber, a liquid heat exchanger and a vapor expulsion unit comsecond upright conduit in thermal relation with said flue, a second connection including said heat exchanger for conducting solution from said second conduit to the inlet of said absorber, said vapor supply line being connected to receive expelled vapor from said second conduit, a lift pipe which is connected at its lower and upper ends to said i'lrst and second conduits, respectively, said first connection being so formed that said rst conduit contains a liquid column whose liquid surface level is above the highest point of said liquid heat exchanger and which freely communicates with the outlet of said absorber by an unbroken liquid body, and said lift pipe having a part in thermal relation with said flue along a Zone extending between the liquid level in said first conduit and the lowest point of the heat exchanger to cause expulsion of vapor from solution in said pipe and raise liquid therein by vapor lift action under the iniiuence of a reaction head formed by the liquid column in said rst conduit, said liquid heat exchanger being in the form of a coil disposed about said heating flue and said first conduit.

l2. In an absorption refrigeration system of the inert gas type including a [vapor] refrigerant vapor supply line, an upright heating flue having a lower heat input end, a circuit for circulation of absorption solution including an absorber, a liquid heat exchanger having a plurality of passages and a vapor expulsion unit comprising a rst upright conduit in the vicinity of said flue, a first connection including one passage of said liquid heat exchanger for conducting solution entirely by gravity flow from the outlet of said absorber to a region of said first conduit removed from the lower end thereof, a second upright conduit in thermal relation with said flue, a second connection including another passage of said liquid heat exchanger for conducting solution from said second conduit to the inlet of said absorber, said vapor supply line being connected to receive vapor from said second conduit, a lift pipe which is connected at its lower and upper ends to said first and second conduits, respectively, said first connection being so formed that said rst conduit contains a liquid column whose liquid surface level is above the region solution is conducted thereto, and said lift pipe having a heat receiving and vapor forming part in thermal relation with said flue along a Zone extending between the liquid surface level in said iirst conduit and the heat input end of said ue to cause expulsion of vapor from solution in said pipe and raise liquid therein by Vapor lift action under the influence of a reaction head formed by the liquid column in said rst conduit, said liquid heat exchanger being in the form of a coil disposed about said heating flue and said rst conduit.

13. An absorption refrigeration system as set forth in claimt 12 in which said liquid -heat ea:- ehanger is in the form of a 'vertically extending coil disposed about said heating flue and said first conduit and the lower end' of said second conduit is connected to the outer passage of said liquid heat exchanger coil at the upper end thereof.

WILHELM GEO-RG KGEL.

(References on following page) 1 1 REFERENCES CITED The following references are of record in the Number le of this patent or the original patent: 550,474 552,966 UNITED STATES PATENTS 5 5571311 Number Name Date 558,338

1,798,946 Maiuri et a1. Mar. 31, 1931 1,802,537 Roos Apr, 28, 1931 12 FOREIGN PATENTS Country Date Great Britain Jan. 8, v1943 Great Britain May 3, 1943 Great Britain Nov. 15, 1943 Great Britain Dec. 31, 1943 

